The Introduction to Harmonics opens with the Orphic tag: I sing for those who understand; shut the doors, uninitiated. The treatise is about notes, intervals, systems, tonoi, modulation, and melopoeia in every genus of harmonia. Anyone whose ear is not already trained in concord and discord should go away and stop his ears.
Voice has a place from gravity to acuteness. Spoken voice runs continuously; intervallic voice stands on the bounds of the places it overleaps and so makes its tension visible. A phthongos is the fall of voice onto one tension. Then come interval, system, the three genera (diatonic, chromatic, enharmonic) with their dieses, the lesser and greater perfect systems (proslambanomenos through nētē hyperbolaion), six concords from the fourth to the double octave, and the story of Pythagoras at the smithy weighing hammers.
Von Jan printed it in the Musici scriptores Graeci (Leipzig, 1895). The treatise is school harmonics — notes, intervals, systems — not astronomical tables.
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